Integrated circuit filler and method thereof

ABSTRACT

Provided is a method for inserting a pre-designed filler cell, as a replacement to a standard filler cell, including identifying at least one gap among a plurality of functional cells. In some embodiments, a pre-designed filler cell is inserted within the at least one gap. By way of example, the pre-designed filler cell includes a layout design having a pattern associated with a particular failure mode. In various embodiments, a layer is patterned on a semiconductor substrate such that the pattern of the layout design is transferred to the layer on the semiconductor substrate. Thereafter, the patterned layer is inspected using an electron beam (e-beam) inspection process.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 15/484,628, filed Apr. 11, 2017, which claims the benefit ofU.S. Provisional Application No. 62/356,964, filed Jun. 30, 2016, thedisclosures of which are hereby incorporated by reference in theirentirety.

BACKGROUND

The electronics industry has experienced an ever increasing demand forsmaller and faster electronic devices which are simultaneously able tosupport a greater number of increasingly complex and sophisticatedfunctions. Accordingly, there is a continuing trend in the semiconductorindustry to manufacture low-cost, high-performance, and low-powerintegrated circuits (ICs). Thus far these goals have been achieved inlarge part by scaling down semiconductor IC dimensions (e.g., minimumfeature size) and thereby improving production efficiency and loweringassociated costs. However, such scaling has also introduced increasedcomplexity to the semiconductor manufacturing process. Thus, therealization of continued advances in semiconductor ICs and devices callsfor similar advances in semiconductor manufacturing processes andtechnology.

In particular, the scaling down of IC dimensions has considerablyincreased the challenges associated with finding defects using existingwafer inspection methods. Wafer inspection may be subdivided into twoprimary technologies—optical inspection and electron beam (e-beam)inspection. While optical inspection has been a semiconductor waferinspection workhorse for many years, e-beam inspection has gainedconsiderable interest, particularly for its ability to detect smallerdefects than those which can be detected using optical inspection. Forexample, e-beam inspection may provide detection of defects down toabout 3 nanometers (nm), whereas optical inspection may begin to havetrouble finding defects smaller than 30 nm. E-beam inspection may alsobe used to detect voltage-contrast type defects, such as electricalshorts or opens at a contact or an interconnect void. The benefits ofe-beam inspection are evident, but there remain challenges. For example,at least some existing e-beam inspection methods suffer from lowinspection sensitivity, low throughput, and/or long analysis cycle time.Thus, existing techniques have not proved entirely satisfactory in allrespects.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when they are read with the accompanying figures.It is noted that, in accordance with the standard practice in theindustry, various features are not drawn to scale. In fact, thedimensions of the various features may be arbitrarily increased orreduced for clarity of discussion.

FIG. 1 is a simplified block diagram of an embodiment of an integratedcircuit (IC) manufacturing system and an associated IC manufacturingflow;

FIG. 2 is a more detailed block diagram of the design house shown inFIG. 1 according to various aspects of the present disclosure;

FIG. 3 shows a high-level flowchart of a method 300 of a generalizeddesign flow, according to various aspects of the present disclosure;

FIGS. 4A/4B illustrate flowcharts of a method 400 and 450 for insertinga redesigned filler cell into an IC layout in accordance with variousembodiments;

FIGS. 5A/5B illustrate portions of an IC layout, demonstrating insertionof the redesigned filler cell into the IC layout, in accordance withsome embodiments; and

FIGS. 6-10 illustrate exemplary layout designs which may be used in theredesigned filler cell, in accordance with some embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

It is also noted that the embodiments described herein may be employedin the design and/or fabrication of any type of integrated circuit, orportion thereof, which may comprise any of a plurality of variousdevices and/or components such as a static random access memory (SRAM)and/or other logic circuits, passive components such as resistors,capacitors, and inductors, and active components such as P-channelfield-effect transistors (PFETs), N-channel FETs (NFETs),metal-oxide-semiconductor field-effect transistors (MOSFETs),complementary metal-oxide-semiconductor (CMOS) transistors, bipolartransistors, high voltage transistors, high frequency transistors,FinFET devices, gate-all-around (GAA) devices, Omega-gate (Ω-gate)devices, or Pi-gate (H-gate) devices, as well as strained-semiconductordevices, silicon-on-insulator (SOI) devices, partially-depleted SOI(PD-SOI) devices, fully-depleted SOI (FD-SOI) devices, other memorycells, or other devices as known in the art. One of ordinary skill mayrecognize other embodiments of semiconductor devices and/or circuits,including the design and fabrication thereof, which may benefit fromaspects of the present disclosure.

The present disclosure is generally related to a method of enhancinge-beam inspection methodology by employing a redesigned filler cell in acircuit layout. Thus, additional embodiments may include an integratedcircuit including the redesigned filler cell. Specifically, embodimentsof the present disclosure provide the redesigned filler cell, as areplacement to a standard filler cell, where the redesigned filler cellincludes a systematic design of experiments (DOE) based on existingand/or potential process failure modes. In semiconductor design,standard cell methodology is a method of designing application-specificintegrated circuits (ASICs) with mostly digital-logic features. Standardcell methodology is an example of design abstraction, whereby alow-level very-large-scale integration (VLSI) layout is encapsulatedinto an abstract logic representation (e.g., such as a NAND gate).Cell-based methodology—the general class to which standard cellsbelong—makes it possible for one designer to focus on the high-level(logical function) aspect of digital design, while another designerfocuses on the implementation (physical) aspect. Along withsemiconductor manufacturing advances, standard cell methodology hashelped designers scale ASICs from comparatively simple single-functionICs (of several thousand gates), to complex multi-million gatesystem-on-a-chip (SoC) devices.

By way of example, a standard cell (e.g., which may be referred to as afunctional cell and/or functional logic cell) is a group of transistorand interconnect structures that provides a boolean logic function(e.g., AND, OR, XOR, XNOR, inverters) or a storage function (flip-flopor latch). The simplest cells are direct representations of theelemental NAND, NOR, and XOR boolean function, although cells of muchgreater complexity are commonly used (e.g., such as a 2-bit full-adder,or muxed D-input flipflop).

In a standard cell layout of an integrated circuit, gaps may be createdbetween standard cells, as it may not be possible to have 100%utilization of the layout and also due to routing congestion. Such gapsmay be filled for a number of reasons, such as for N-well continuity, toimprove feature uniformity across a wafer, to ensure that power andground signals are coupled to other functional cells, to reduce issuesrelated to semiconductor yield, as well as for a variety of otherreasons. In various cases, the gaps described above may be filled usingstandard filler cells, which may include non-functional filler cells. Asdescribed in more detail herein, embodiments of the present disclosureare directed to a method of enhancing e-beam inspection methodology byemploying a redesigned filler cell in a circuit layout, for example, toincrease in-line process issue identification capability.

While wafer inspection using optical inspection techniques has beenpredominantly used for many years, e-beam inspection has gainedconsiderable interest, particularly for its ability to detect smallerdefects than those which can be detected using optical inspection. Forexample, e-beam inspection may provide detection of defects down toabout 3 nanometers (nm), whereas optical inspection may begin to havetrouble finding defects smaller than 30 nm. E-beam inspection may alsobe used to detect voltage-contrast type defects, such as electricalshorts or opens at a contact or an interconnect void. Despite thebenefits of e-beam inspection, challenges remain. For example, at leastsome existing e-beam inspection methods suffer from low inspectionsensitivity (e.g., due to global recipe tuning), low throughput (e.g.,due to additional scanning/inspection time spent on healthy cells),and/or long analysis cycle time due to non-repeating inspected patterns.Embodiments of the present disclosure offer advantages over the existingart, though it is understood that other embodiments may offer differentadvantages, not all advantages are necessarily discussed herein, and noparticular advantage is required for all embodiments. For example, atleast some embodiments provide the redesigned filler cell, as areplacement to a standard filler cell, where the redesigned filler cellincludes a systematic design of experiments (DOE) based on existingand/or potential process failure modes. In some examples, the standardfiller cells may be replaced by the redesigned filler cells at anauto-place and route (APR) stage of a design flow. In variousembodiments, the APR stage of the design flow includes a process wherebya gate-level netlist (e.g., obtained from a synthesis tool) isphysically implemented in a circuit layout by placing cells andauto-routing the cells based on the connections inferred from thenetlist. By employing the redesigned filler cell, embodiments of thepresent disclosure can convert irregular logic patterns into repeatedarrays (e.g., conceptually repeated arrays), such as in the case of anSRAM chip, thereby providing a number of benefits. For example, at leastsome advantages include no additional cost in terms of chip utilization,improved e-beam inspection sensitivity (e.g., due to repeatedarrays/patterns), increased throughput (e.g., due to no additionalinspection time for healthy cells), and shorter analysis cycle time(e.g., due to cell-to-cell comparison which may more quickly provide agood/no-good cell determination). Thus, embodiments of the presentdisclosure provide an enhanced e-beam inspection methodology. It isunderstood that the disclosed advantages are merely exemplary, andadditional advantages may be evident to those skilled in the art havingbenefit of this disclosure.

Referring now to FIG. 1, illustrated therein is a simplified blockdiagram of an embodiment of an integrated circuit (IC) manufacturingsystem 100 and an IC manufacturing flow associated therewith, which maybenefit from various aspects of the present disclosure. The ICmanufacturing system 100 includes a plurality of entities, such as adesign house 120, a mask house 130, and an IC manufacturer 150 (i.e., afab), that interact with one another in the design, development, andmanufacturing cycles and/or services related to manufacturing anintegrated circuit (IC) device 160. The plurality of entities areconnected by a communications network, which may be a single network ora variety of different networks, such as an intranet and the Internet,and may include wired and/or wireless communication channels. Eachentity may interact with other entities and may provide services toand/or receive services from the other entities. One or more of thedesign house 120, mask house 130, and IC manufacturer 150 may have acommon owner, and may even coexist in a common facility and use commonresources.

In various embodiments, the design house 120, which may include one ormore design teams, generates an IC design layout 122. The IC designlayout 122 may include various geometrical patterns designed for thefabrication of the IC device 160. By way of example, the geometricalpatterns may correspond to patterns of metal, oxide, or semiconductorlayers that make up the various components of the IC device 160 to befabricated. The various layers combine to form various features of theIC device 160. For example, various portions of the IC design layout 122may include features such as an active region, a gate electrode, sourceand drain regions, metal lines or vias of a metal interconnect, openingsfor bond pads, as well as other features known in the art which are tobe formed within a semiconductor substrate (e.g., such as a siliconwafer) and various material layers disposed on the semiconductorsubstrate. Additionally, the IC design layout 122 may include theredesigned filler cell, in accordance with embodiments of the presentdisclosure. In various examples, the design house 120 implements adesign procedure to form the IC design layout 122. The design proceduremay include logic design, physical design, and/or place and route.Additional details of the design house 120 design procedure and the ICdesign layout 122, including the redesigned filler cell, are describedin more detail below. The IC design layout 122 may be presented in oneor more data files having information related to the geometricalpatterns which are to be used for fabrication of the IC device 160. Insome examples, the IC design layout 122 may be expressed in a GDSII fileformat or DFII file format.

In some embodiments, the design house 120 may transmit the IC designlayout 122 to the mask house 130, for example, via the networkconnection described above. The mask house 130 may then use the ICdesign layout 122 to manufacture one or more masks, which include theredesigned filler cell, to be used for fabrication of the various layersof the IC device 160 according to the IC design layout 122. In variousexamples, the mask house 130 performs mask data preparation 132, wherethe IC design layout 122 is translated into a form that can bephysically written by a mask writer, and mask fabrication 144, where thedesign layout prepared by the mask data preparation 132 is modified tocomply with a particular mask writer and/or mask manufacturer and isthen fabricated. In the example of FIG. 1, the mask data preparation 132and mask fabrication 144 are illustrated as separate elements; however,in some embodiments, the mask data preparation 132 and mask fabrication144 may be collectively referred to as mask data preparation.

In some examples, the mask data preparation 132 includes application ofone or more resolution enhancement technologies (RETs) to compensate forpotential lithography errors, such as those that can arise fromdiffraction, interference, or other process effects. In some examples,optical proximity correction (OPC) may be used to adjust line widthsdepending on the density of surrounding geometries, add “dog-bone”end-caps to the end of lines to prevent line end shortening, correct forelectron beam (e-beam) proximity effects, or for other purposes as knownin the art. For example, OPC techniques may add sub-resolution assistfeatures (SRAFs), which for example may include adding scattering bars,serifs, and/or hammerheads to the IC design layout 122 according tooptical models or rules such that, after a lithography process, a finalpattern on a wafer is improved with enhanced resolution and precision.The mask data preparation 132 may also include further RETs, such asoff-axis illumination (OAI), phase-shifting masks (PSM), other suitabletechniques, or combinations thereof.

After mask data preparation 132 and during mask fabrication 144, a maskor a group of masks may be fabricated based on the IC design layout 122which includes the redesigned filler cell. For example, an electron-beam(e-beam) or a mechanism of multiple e-beams is used to form a pattern ona mask (photomask or reticle) based on the IC design layout 122including the redesigned filler cell. The mask can be formed in varioustechnologies. In an embodiment, the mask is formed using binarytechnology. In some embodiments, a mask pattern includes opaque regionsand transparent regions. A radiation beam, such as an ultraviolet (UV)beam, used to expose a radiation-sensitive material layer (e.g.,photoresist) coated on a wafer, is blocked by the opaque region andtransmitted through the transparent regions. In one example, a binarymask includes a transparent substrate (e.g., fused quartz) and an opaquematerial (e.g., chromium) coated in the opaque regions of the mask. Insome examples, the mask is formed using a phase shift technology. In aphase shift mask (PSM), various features in the pattern formed on themask are configured to have a pre-configured phase difference to enhanceimage resolution and imaging quality. In various examples, the phaseshift mask can be an attenuated PSM or alternating PSM.

In some embodiments, the IC manufacturer 150, such as a semiconductorfoundry, uses the mask (or masks) fabricated by the mask house 130 totransfer one or more mask patterns, including a redesigned filler cellpattern, onto a production wafer 152 and thus fabricate the IC device160 on the production wafer 152. The IC manufacturer 150 may include anIC fabrication facility that may include a myriad of manufacturingfacilities for the fabrication of a variety of different IC products.For example, the IC manufacturer 150 may include a first manufacturingfacility for front end fabrication of a plurality of IC products (i.e.,front-end-of-line (FEOL) fabrication), while a second manufacturingfacility may provide back end fabrication for the interconnection andpackaging of the IC products (i.e., back-end-of-line (BEOL)fabrication), and a third manufacturing facility may provide otherservices for the foundry business (e.g., research and development). Invarious embodiments, the semiconductor wafer (i.e., the production wafer152) within and/or upon which the IC device 160 is fabricated mayinclude a silicon substrate or other substrate having material layersformed thereon. Other substrate materials may include another suitableelementary semiconductor, such as diamond or germanium; a suitablecompound semiconductor, such as silicon carbide, indium arsenide, orindium phosphide; or a suitable alloy semiconductor, such as silicongermanium carbide, gallium arsenic phosphide, or gallium indiumphosphide. In some embodiments, the semiconductor wafer may furtherinclude various doped regions, dielectric features, and multilevelinterconnects (formed at subsequent manufacturing steps).

Moreover, the mask (or masks) may be used in a variety of processes. Forexample, the mask (or masks) may be used to pattern various layers, inan ion implantation process to form various doped regions in thesemiconductor wafer, in an etching process to form various etchingregions in the semiconductor wafer, and/or in other suitable processes.As such, the redesigned filler cell pattern may be transferred onto anyof a plurality of layers (e.g., metal, insulator, etc.) of theproduction wafer 152 during the manufacturing process. In addition, awafer inspection 154 facility (e.g., such as an e-beam inspectionfacility) of the IC manufacturer 150 may be used to inspect theproduction wafer 152 during various stages of processing, for example,to detect defects (e.g., such as random or systematic defects). By wayof example, if the wafer inspection 154 finds a defect present on theproduction wafer 152, the defect may be removed (e.g., by a defectremoval tool), the production wafer 152 may be reprocessed, or otherappropriate processing may be performed. In accordance with embodimentsof the present disclosure, use of the redesigned filler cell providesfor improved e-beam inspection sensitivity, increased throughput, andshorter analysis cycle time. Thus, embodiments of the present disclosureprovide an enhanced e-beam inspection methodology, thereby improving thecapabilities of the wafer inspection 154 facility.

Referring now to FIG. 2, provided therein is a more detailed blockdiagram of the design house 120 shown in FIG. 1 according to variousaspects of the present disclosure. In the example of FIG. 2, the designhouse 120 includes an IC design system 180 that is operable to performthe functionality described in association with the design house 120 ofFIG. 1 and in association with methods 300, 400, and 450 of FIGS.3/4A/4B, discussed below. The IC design system 180 is an informationhandling system such as a computer, server, workstation, or othersuitable device. The system 180 includes a processor 182 that iscommunicatively coupled to a system memory 184, a mass storage device186, and a communication module 188. The system memory 184 provides theprocessor 182 with non-transitory, computer-readable storage tofacilitate execution of computer instructions by the processor. Examplesof system memory may include random access memory (RAM) devices such asdynamic RAM (DRAM), synchronous DRAM (SDRAM), solid state memorydevices, and/or a variety of other memory devices known in the art.Computer programs, instructions, and data are stored within the massstorage device 186. Examples of mass storage devices may include harddiscs, optical disks, magneto-optical discs, solid-state storagedevices, and/or a variety other mass storage devices known in the art.The communication module 188 is operable to communicate information suchas IC design layout files with the other components in the ICmanufacturing system 100, such as mask house 130. Examples ofcommunication modules may include Ethernet cards, 802.11 WiFi devices,cellular data radios, and/or other suitable devices known in the art.

In operation, the IC design system 180 is configured to provide the ICdesign layout 122, including the redesigned filler cell. In such anembodiment, the IC design system 180 provides the IC design layout 122,which may be in the form of a GDSII file 194 and which includes theredesigned filler cell, to the mask house 130. As such, the mask house130 may use the provided IC design layout to manufacture one or moremasks, which include the redesigned filler cell. In alternativeembodiments, the IC design layout 122 may be transmitted between thecomponents in the IC manufacturing system 100 in alternate file formatssuch as DFII, CIF, OASIS, or any other suitable file type. Further, theIC design system 180, the IC design house 120, and the mask house 130may include additional and/or different components in alternativeembodiments.

Referring now to FIG. 3, illustrated therein is a flow chart of a method300 that may be implemented by the design house 120 to provide the ICdesign layout 122, including the redesigned filler cell, in accordancewith various embodiments. By way of example, the method 300 includes ageneralized physical design flow and/or ASIC design flow. The method 300begins at block 302 where a design is entered, for example, by way of ahardware description language (e.g., VHDL, Verilog, and/orSystemVerilog). The design entered using the hardware descriptionlanguage may be referred to as register transfer level (RTL) design. Insome cases, functional/logical verification may be performed after theRTL design. The method 300 then proceeds to block 304 where synthesis isperformed to generate a netlist (e.g., a gate-level netlist). In someexamples, a synthesis tool takes the RTL hardware description and astandard cell library as inputs and generates a gate-level netlist as anoutput. The method proceeds to block 306 where partitioning isperformed, for example, to separate various functional blocks.Thereafter, the method proceeds to block 308 where floorplanning isperformed. By way of example, floorplanning is the process ofidentifying structures that should be placed close together, andallocating space for them in such a manner as to meet the sometimesconflicting goals of available space, required performance, and thedesire to have various structures close to one another. Merely forpurposes of illustration, the method 300 shows that insertion of theredesigned filler cells (block 320) may be performed immediatelyfollowing the floorplanning step (block 308). To be sure, and asdiscussed below, insertion of the redesigned filler cells (block 320)may be performed before, after, or during any of the steps of the method300. As such, the block 320 of the method 300 is illustrated using adashed line. The method 300 may then proceed to block 310 whereplacement is performed. Placement may be used to assign locations tovarious circuit components on a chip. In various examples, placement mayaim to optimize a total wirelength, timing, congestion, power, as wellas to accomplish other objectives. The method may then proceed to block312 where routing is performed. Routing is used to add wiring (e.g.,electrical connections) between the previously placed components whilesatisfying IC design rules. Additional operations can be providedbefore, during, and after the method 300, and some operations describedcan be replaced, eliminated, or moved around for additional embodimentsof the method. For example, the method 300 may also include clock-treesynthesis, physical verification, timing analysis, GDSII generation, orother suitable steps. It is also noted that the method 300 is exemplary,and is not intended to limit the present disclosure beyond what isexplicitly recited in the claims that follow.

As previously described, gaps may be created between standard cells ofan IC design layout (e.g., the IC design layout 122), as it may not bepossible to have 100% utilization of the layout and also due to routingcongestion. In at least some existing methods, a non-used or standardfiller cell may be used to fill in these gaps. In embodiments of thepresent disclosure, such standard filler cells may be replaced by apre-designed cell (e.g., the redesigned filler cell discussed above),for example, to increase in-line e-beam inspection sensitivity. Invarious embodiments, the redesigned filler cell includes a systematicdesign of experiments (DOE) based on existing and/or potential processfailure modes, for example, for a given material layer, for a givensection of the IC layout, for a given device or set of devices, etc. Asdiscussed above and in some cases, the standard filler cells arereplaced by the redesigned cells after the floor planning step (block308) and before the placement step (block 310) of the method 300.Alternatively, in some examples, the standard filler cells may bereplaced by the redesigned cells as part of the placement step (block310). In some embodiments, the standard filler cells may not be placed,then replaced, by the redesigned cells, but instead the redesigned cellsmay be placed straightaway at a point in the design (e.g., the method300) when the standard filler cell would have normally been placed.Generally, as previously discussed, the redesigned filler cell(s) may beplaced before, after, or during any of the steps of the method 300. Insome examples, a layout design that includes the standard filler cellsmay be redesigned such that the standard filler cells are removed andreplaced by the redesigned cells. Regardless of when the redesignedfiller cell(s) are inserted into the IC layout design, the presentdisclosure provides one or more methods for such insertion, as describedin more detail below.

In particular, and with reference to FIGS. 4A and 4B, illustratedtherein are exemplary methods 400 and 450, respectively, for inserting aredesigned filler cell in accordance with various embodiments. By way ofexample, the method 400 provides a method for inserting the redesignedfiller cell at a particular stage of the physical design flow (e.g., themethod 300), while the method 450 provides an alternative method forinserting the redesigned filler cell at another stage of the physicaldesign flow. Additional operations can be provided before, during, andafter the methods 400 and 450, and some operations described can bereplaced, eliminated, or moved around for additional embodiments of themethod. It is also noted that the methods 400 and 450 are exemplary, andare not intended to limit the present disclosure beyond what isexplicitly recited in the claims that follow. Various aspects of themethods 400 and 450 are described below with reference to FIGS. 5A, 5B,and 6-10.

Beginning with the method 400 shown in FIG. 4A, the method 400 begins atblock 402 where at least one gap is identified among a plurality offunctional cells. Referring to the example of FIG. 5A, and in anembodiment of block 402, a portion of IC layout 522 is shown whichincludes a plurality of standard cells labeled ‘STD CELL’, and a gaplabeled ‘GAP’ disposed among and/or between the standard cells. Aspreviously noted, the standard cells, which may be referred to as afunctional cell and/or functional logic cell, may include a group oftransistor and interconnect structures that can provide any of a numberof simple to complex circuit functions. Stated another way, the standardcells may be referred to as portions of a circuit of the IC layout 522.Gaps, such as the gap shown in FIG. 5A, may occur because it may not bepossible to have 100% utilization of the layout and also due to routingcongestion. FIG. 5A also illustrates a dummy cell, where in at leastsome embodiments, a spacing between the dummy cell and an adjacentstandard cell is greater than or equal to about 0.2 microns.

The method 400 proceeds to block 404 where a pre-designed filler cell(e.g., the redesigned filler cell discussed above) is placed with thegap identified at block 402. In addition, the redesigned filler cellincludes a layout design related to a particular failure mode. Aspreviously discussed, it is desirable to fill the identified gaps for anumber of reasons, such as for N-well continuity, to improve featureuniformity across a wafer, to ensure that power and ground signals arecoupled to other functional cells, to reduce issues related tosemiconductor yield, as well as for a variety of other reasons. In atleast some conventional methods, such gaps may be filled using standardfiller cells, which may include non-functional filler cells. However, inaccordance with embodiments of the present disclosure, a redesignedfiller cell is placed at block 404 instead of a standard filler cell. Tobe sure, in some embodiments, a combination of one or more redesignedfiller cells and one or more standard filler cells may be placed withinone or more gaps of the IC layout. Referring to the example of FIG. 5B,and in an embodiment of block 404, a redesigned filler cell 524 and astandard filler cell 526 are placed within the gap labeled ‘GAP’disposed among and/or between the standard cells. As discussed in moredetail below, the redesigned filler cell 524 may have a layoutcorresponding to an existing and/or potential failure mode. Moreover,the redesigned filler cell 524 may have a layout corresponding to anexisting and/or potential failure mode within one or more of thestandard cells adjacent to the redesigned filler cell 524. Statedanother way, a failure mode in at least one adjacent standard cells maybe first identified, and then an appropriate redesigned filler cell maybe selected, where the selected redesigned filler cell has a layoutcorresponding to the identified failure mode in the adjacent standardcell. While the redesigned filler cell 524 is illustrated as beinglarger in size than the standard filler cell 526, the sizes shown arenot meant to be limiting in any way. In some examples, the redesignedfiller cell 524 is larger than the standard filler cell 526. In somecases, the standard filler cell 526 is not used. Thus, in some examples,the gap may be filled entirely with a plurality of redesigned fillercells which may be the same or different redesigned filler cell, forexample, targeted to identifying the same or different failure mode.

Referring now to FIGS. 6-10, additional details are provided regardingthe redesigned filler cell (e.g., such as the redesigned filler cell524). In particular, FIGS. 6-10 provide examples of various layoutdesigns which may be used, in accordance with embodiments of thisdisclosure, to identify one or more failure modes during a subsequente-beam inspection process. It is understood that the failure modesdiscussed, as well as the associated layout designed used for acorresponding redesigned filler cell, are merely exemplary. Those ofskill in the art having the benefit of this disclosure will recognizeother failure modes, as well as other suitable layout designs which maybe used for the redesigned filler cell.

Generally, and in various embodiments, the redesigned filler cellsdescribed herein may include designs that are customized, as needed,according to a particular type of failure mode. In particular, a varietyof different types of failure modes may be more common within a certainlayer (e.g., a metal layer, a VIA layer, an ILD layer, etc.) and/orwithin a certain circuit area, thus the pre-designed filler cells may bedesigned as-needed and in accordance with one or more failure modes thatrequire closer inspection (e.g., in some cases, within a given layerand/or circuit area). By way of example, some failure modes may includea line (e.g., which may be a metal line), over-etch/under-etch, a linespacing, a line extrusion, a line pattern and/or size, or other failuremodes such as a VIA spacing, pattern/size, over/under-etch, thresholdvoltage failure (e.g., layer defect that may cause threshold voltage tobe outside of a specification value), as well as other device and/orcircuit failure modes. In some cases, and depending on the type offailure mode of concern, the pre-designed filler cell may include acustom layout design having a layout pattern designed to provide anoptimal e-beam inspection sensitivity (e.g., for the particular type offailure mode associated with the custom layout design). In variousexamples, the pre-designed filler cell may include a functional ornon-functional cell.

With reference now to FIG. 6, illustrated therein is a redesigned fillercell layout 600 corresponding to a first failure mode, such as a ‘MD-MG’failure mode. By way of example, ‘MD’ may refer to a connection from ametal layer to a source/drain region, thus it may be similar to acontact metal. ‘MG’ may refer to a metal gate. To be sure, a materialused for ‘MG’ may include a metal layer and/or a polysilicon layer.Thus, the ‘MD-MG’ failure mode may be a layout design optimized fordetection of an ‘MD-MG’ electrical short (e.g., an electrical shortbetween a source/drain metal and a metal gate). Referring specificallyto FIG. 6, identified therein are ‘MD’ features 602 having a lengthidentified as ‘1’, poly features 604 (e.g., as for a poly-gate), polycontacts 606, a metal-on-poly ‘MP’ feature 608 having a lengthidentified as ‘2’, a p-type device region ‘P’ and an n-type deviceregion ‘N’ identified as ‘3’, a cut poly ‘CPO’ feature 610, active areas612 having an active area space identified as ‘5’. It is noted onceagain that the features, layers, and dimensions illustrated in FIG. 6are merely exemplary, and other features, layers, and/or dimensions maybe used, for example, in accordance with a particular technology orprocess to identify the specified failure mode (e.g., the ‘MD-MG’failure mode). It is also noted that similar features/layers shown inFIGS. 7-10 may have similar element numbers for ease of reference.

Referring to FIG. 7, illustrated therein is a redesigned filler celllayout 700 corresponding to a second failure mode, such as an ‘MGExtrusion’ failure mode. Referring specifically to FIG. 7, identifiedtherein are a poly feature ‘PO’ identified as ‘1’, an active area spaceidentified as ‘2’, an N+ p-well region identified as ‘3’, and a P+n-wellregion identified as ‘4’. The features, layers, and dimensionsillustrated in FIG. 7 are merely exemplary, and other features, layers,and/or dimensions may be used, for example, in accordance with aparticular technology or process to identify the specified failure mode(e.g., the ‘MG Extrusion’ failure mode).

Referring to FIG. 8, illustrated therein is a redesigned filler celllayout 800 corresponding to a third failure mode, such as an ‘MDunder-etch’ failure mode used to identify a contact under-etch failure.Referring specifically to FIG. 8, identified therein are the ‘MD’features 602 having a length identified as ‘1’, poly features 604,active areas 612, MD contacts 802, as well as other MD features,including a region without MD ‘w/o MD’. The features, layers, anddimensions illustrated in FIG. 8 are merely exemplary, and otherfeatures, layers, and/or dimensions may be used, for example, inaccordance with a particular technology or process to identify thespecified failure mode (e.g., the ‘MD under-etch’ failure mode).

With reference to FIG. 9, illustrated therein is a redesigned fillercell layout 900 corresponding to a fourth failure mode, such as a ‘CPO’failure mode. Thus, the layout 900 may be used as a cut poly failmonitor. Referring specifically to FIG. 9, identified therein are cutpoly (CPO) features 610 having a length identified as ‘1’, and polyfeatures 604 ‘PO’, as well as other features/layers. The features,layers, and dimensions illustrated in FIG. 9 are merely exemplary, andother features, layers, and/or dimensions may be used, for example, inaccordance with a particular technology or process to identify thespecified failure mode (e.g., the ‘CPO’ failure mode).

Referring to FIG. 10, illustrated therein is a redesigned filler celllayout 1000 corresponding to a fifth failure mode, such as a cut MD‘CMD’ failure mode. Thus, the layout 1000 may be used as a cut MD failmonitor. Referring specifically to FIG. 10, identified therein are ‘CMD’features 1002, ‘CMD’ features 1004 having a length identified as ‘1’, aswell as other CMD patterns/features. The features, layers, anddimensions illustrated in FIG. 10 are merely exemplary, and otherfeatures, layers, and/or dimensions may be used, for example, inaccordance with a particular technology or process to identify thespecified failure mode (e.g., the ‘CMD’ failure mode).

It is also noted that each of the redesigned filler cell layouts 600,700, 800, 900, and 1000 provide repeated arrays (e.g., a repeatedpattern array), thereby reducing analysis cycle time of cell-to-cellcomparisons during e-beam inspection of a layer patterned using any ofthe layouts 600, 700, 800, 900, and/or 1000, and thereby improving thesubsequent e-beam inspection process. In other words, the failuremode(s) for which the layouts 600, 700, 800, 900, 1000 are designed maybe more rapidly detected, within a patterned layer, using e-beaminspection and the redesigned filler cell layouts 600, 700, 800, 900,and/or 1000. As previously noted, the failure modes discussed, as wellas the associated layouts (e.g., the layouts 600, 700, 800, 900, 1000)used for a corresponding redesigned filler cell, are merely exemplary.In some embodiments, a custom-designed redesigned filler cell layout maybe provided, for example, once information regarding a particularprocessing issue/failure mode is known and/or determined. In addition,placement of a redesigned filler cell (at block 404) having a layoutassociated with a particular failure mode may be done in such a way thatthe redesigned filler cell layout chosen corresponds to an existingand/or potential failure mode present in the standard cells (e.g., STDCELL) adjacent to the redesigned filler cell (e.g., the redesignedfiller cell 524) placed in the gap.

The method 400 proceeds to block 406 where a layer on a semiconductorsubstrate is patterned in accordance with the layout design related tothe particular failure mode, based on the redesigned filler cell. Asdiscussed above, one or more masks may be fabricated that include theredesigned filler cell layout (e.g., the redesigned filler cell 524).Thereafter, the IC manufacturer 150, such as a semiconductor foundry,may use the mask (e.g., fabricated by the mask house 130) to transferone or more mask patterns (e.g., using a photolithography and etchprocess), including the redesigned filler cell pattern, onto asemiconductor wafer (e.g., the production wafer 152). Generally, theredesigned filler cell layout pattern may be transferred onto any of aplurality of layers (e.g., metal, insulator, etc.) of the productionwafer 152 during the manufacturing process.

The method 400 proceeds to block 408 where the patterned layer (block406) is inspected using an e-beam inspection process. In particular,after patterning of a particular layer of a semiconductor wafer with theredesigned filler cell layout, the wafer may be inspected (e.g., by thewafer inspection 154 facility including an e-beam inspection facility).By way of example, if the wafer inspection 154 finds a defect present onthe production wafer 152, the defect may be removed (e.g., by a defectremoval tool), the production wafer 152 may be reprocessed, or otherappropriate processing may be performed. In accordance with embodimentsof the present disclosure, use of the redesigned filler cell providesfor improved e-beam inspection sensitivity, increased throughput, andshorter analysis cycle time, due at least in part to the repeated arraysprovided in the redesigned filler cells. Thus, embodiments of thepresent disclosure provide an enhanced e-beam inspection methodology.

With reference to FIG. 4B, the method 450 is substantially similar tothe method 400 of FIG. 4A. Thus, for clarity of discussion, focus isgiven here to the differences between the methods 400 and 450. Inparticular, in the method 450, one or more standard filler cells mayhave already been used to fill the gap(s) between/among functional cells(e.g., standard cells), and the method 450 provides for removing suchstandard filler cells and replacing them with one or more redesignedfiller cells. Thus, by way of example, the method 450 begins at block452 where a standard filler cell disposed in a gap between functionalcells is identified (e.g., by the IC design system 180). The method 450proceeds to block 454 where the identified standard filler cell isremoved and replaced by a redesigned filler cell (e.g., by the IC designsystem 180). The redesigned filler cell includes a layout design relatedto a particular failure mode, as described above. Thereafter, the method450 may proceed to block 456 where a layer on a semiconductor substrateis patterned in accordance with the layout design related to theparticular failure mode, based on the redesigned filler cell, asdiscussed above. The method 450 then proceeds to block 458 where thepatterned layer (block 456) is inspected using an e-beam inspectionprocess, as discussed above.

In addition, the various embodiments disclosed herein, including themethods 300, 400, and 450, may be implemented on any suitable computingsystem, such as the IC design system 180 described in association withFIG. 2. In some embodiments, the methods 300, 400, and 450 may beexecuted on a single computer, local area networks, client-servernetworks, wide area networks, internets, hand-held and other portableand wireless devices and networks. Such a system architecture may takethe form of an entirely hardware embodiment, an entirely softwareembodiment, or an embodiment containing both hardware and softwareelements. By way of example, hardware generally includes at leastprocessor-capable platforms, such as client-machines (also known aspersonal computers or servers), and hand-held processing devices (suchas smart phones, personal digital assistants (PDAs), or personalcomputing devices (PCDs), for example. In addition, hardware may includeany physical device that is capable of storing machine-readableinstructions, such as memory or other data storage devices. Other formsof hardware include hardware sub-systems, including transfer devicessuch as modems, modem cards, ports, and port cards, for example. Invarious examples, software generally includes any machine code stored inany memory medium, such as RAM or ROM, and machine code stored on otherdevices (such as floppy disks, flash memory, or a CD-ROM, for example).In some embodiments, software may include source or object code, forexample. In addition, software may encompass any set of instructionscapable of being executed in a client machine or server.

Furthermore, embodiments of the present disclosure can take the form ofa computer program product accessible from a tangible computer-usable orcomputer-readable medium providing program code for use by or inconnection with a computer or any instruction execution system. For thepurposes of this description, a tangible computer-usable orcomputer-readable medium may be any apparatus that can contain, store,communicate, propagate, or transport the program for use by or inconnection with the instruction execution system, apparatus, or device.The medium may be an electronic, magnetic, optical, electromagnetic,infrared, a semiconductor system (or apparatus or device), or apropagation medium.

In some embodiments, defined organizations of data known as datastructures may be provided to enable one or more embodiments of thepresent disclosure. For example, a data structure may provide anorganization of data, or an organization of executable code. In someexamples, data signals may be carried across one or more transmissionmedia and store and transport various data structures, and may thus beused to transport an embodiment of the present disclosure.

The embodiments of the present disclosure offer advantages over existingart, though it is understood that other embodiments may offer differentadvantages, not all advantages are necessarily discussed herein, andthat no particular advantage is required for all embodiments. By thedisclosed method of enhancing e-beam inspection methodology by employinga redesigned filler cell, various shortcomings of at least somecurrently-employed methods are effectively overcome. For example,embodiments of the present disclosure provide a redesigned filler cell,as a replacement to a standard filler cell, where the redesigned fillercell includes a systematic design of experiments (DOE) based on existingand/or potential process failure modes (e.g., of adjacentfunctional/standard cells). By employing the redesigned filler cell,embodiments of the present disclosure can convert irregular logicpatterns into repeated arrays, thereby providing a number of benefits.For example, at least some advantages include no additional cost interms of chip utilization, improved e-beam inspection sensitivity (e.g.,due to repeated arrays/patterns), increased throughput (e.g., due to noadditional inspection time for healthy cells), and shorter analysiscycle time (e.g., due to cell-to-cell comparison which may more quicklyprovide a good/no-good cell determination). Thus, embodiments of thepresent disclosure provide an enhanced e-beam inspection methodology.Those of skill in the art will readily appreciate that the methodsdescribed herein may be applied to a variety of other semiconductorlayouts, semiconductor devices, and semiconductor processes toadvantageously achieve similar benefits to those described hereinwithout departing from the scope of the present disclosure.

Thus, one of the embodiments of the present disclosure described amethod for fabricating a semiconductor device including identifying atleast one gap among a plurality of functional cells. In someembodiments, a pre-designed filler cell is inserted within the at leastone gap. By way of example, the pre-designed filler cell includes alayout design having a pattern associated with a particular failuremode. In various embodiments, a layer is patterned on a semiconductorsubstrate such that the pattern of the layout design is transferred tothe layer on the semiconductor substrate. Thereafter, the patternedlayer is inspected using an electron beam (e-beam) inspection process.

In another of the embodiments, discussed is a method for fabricating asemiconductor device including identifying a standard filler celldisposed in a gap between a plurality of functional cells. In someembodiments, the standard filler cell is removed and a redesigned fillercell is inserted within the gap between the plurality of functionalcells. In various examples, the redesigned filler cell includes a layoutpattern associated with a particular failure mode. In some embodiments,a substrate layer is patterned such that the layout pattern istransferred to the substrate layer, and the patterned layer isinspected.

In yet other embodiments, discussed is an integrated circuit (IC)including a plurality of functional cells having at least one gapdisposed adjacent to at least one functional cell of the plurality offunctional cells and a pre-designed filler cell disposed within the atleast one gap. By way of example, the pre-designed filler cell includesa layout design associated with a particular failure mode. In addition,the particular failure mode may include a potential failure mode of theat least one functional cell. In some embodiments, the layout designincludes a repeated pattern array.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. An integrated circuit, comprising: a plurality offunctional cells including at least one gap disposed adjacent to atleast one functional cell of the plurality of functional cells; apre-designed filler cell disposed within the at least one gap, whereinthe pre-designed filler cell is associated with a particular failuremode, and wherein the particular failure mode includes a potentialfailure mode of the at least one functional cell; and a standard fillercell disposed within the at least one gap.
 2. The integrated circuit ofclaim 1, wherein the pre-designed filler cell includes a repeatedpattern array.
 3. The integrated circuit of claim 1, further comprising:a plurality of gaps disposed among the plurality of functional cells;and a plurality of pre-designed filler cells, wherein at least onepre-designed filler cell of the plurality of pre-designed filler cellsis disposed within each of the plurality of gaps and is adjacent to aparticular functional cell, and wherein the at least one pre-designedfiller cell is associated with a potential failure mode of the adjacentparticular functional cell.
 4. The integrated circuit of claim 1,wherein the plurality of functional cells define at least part of astatic random access memory (SRAM).
 5. The integrated circuit of claim1, wherein the standard filler cell includes an irregular pattern. 6.The integrated circuit of claim 1, wherein the pre-designed filler cellis configured to enhance electron beam (e-beam) inspection sensitivityfor the particular failure mode.
 7. The integrated circuit of claim 1,wherein the particular failure mode includes at least one of anelectrical short failure mode, a metal extrusion failure mode, anunder-etch failure mode, an over-etch failure mode, a cut-poly failuremode, a cut-metal failure mode, a line spacing failure mode, a linepattern failure mode, and a threshold voltage failure mode.
 8. Theintegrated circuit of claim 1, wherein the pre-designed filler cellprovides well continuity between at least some of the plurality offunctional cells.
 9. The integrated circuit of claim 1, furthercomprising a dummy cell spaced at least 0.2 microns from the pluralityof functional cells.
 10. The integrated circuit of claim 1, wherein theplurality of functional cells and the pre-designed filler cell aredisposed within a semiconductor substrate.
 11. A semiconductor device,comprising: a substrate having a patterned layer disposed thereon;wherein the patterned layer includes a first patterned region definingat least one functional cell; wherein the patterned layer includes asecond patterned region adjacent to the first patterned region, whereinthe second patterned region defines a pre-designed filler cell includinga repeated pattern array, and wherein the pre-designed filler cell isassociated with a failure mode of the at least one functional cell; andwherein the patterned layer further includes a third patterned regionadjacent to the second patterned region, and wherein the third patternedregion defines a standard filler cell.
 12. The semiconductor device ofclaim 11, wherein the standard filler cell includes an irregularpattern.
 13. The semiconductor device of claim 11, wherein thesemiconductor device includes a static random access memory (SRAM). 14.The semiconductor device of claim 11, wherein the pre-designed fillercell provides well continuity between the at least one functional celland another functional cell.
 15. The semiconductor device of claim 11,wherein the pre-designed filler cell provides at least one of a powersignal and a ground signal to the at least one functional cell.
 16. AnSRAM circuit, comprising: a patterned region including a plurality offunctional cells, wherein the plurality of functional cells occupy afirst portion of the patterned region; and a plurality of filler cellsthat occupy a second portion of the patterned region different than thefirst portion, wherein each of the plurality of filler cells include arepeated pattern array; at least one standard filler cell within thesecond portion of the patterned region; and wherein each of theplurality of filler cells is associated with a particular failure mode,and wherein the particular failure mode of a given filler cell includesa potential failure mode of a functional cell adjacent to the givenfiller cell.
 17. The SRAM circuit of claim 16, wherein the at least onestandard filler cell includes an irregular pattern.
 18. The SRAM circuitof claim 16, wherein the plurality of filler cells includes a pluralityof pre-designed filler cells.
 19. The SRAM circuit of claim 16, whereinthe particular failure mode includes at least one of an electrical shortfailure mode, a metal extrusion failure mode, an under-etch failuremode, an over-etch failure mode, a cut-poly failure mode, a cut-metalfailure mode, a line spacing failure mode, a line pattern failure mode,and a threshold voltage failure mode.
 20. The SRAM circuit of claim 16,further comprising a dummy cell spaced at least 0.2 microns from theplurality of functional cells.